Electric source devices for fire alarm systems

ABSTRACT

A fire alarm system uses a detector operated from a regulated voltage supply which maintains the sensitivity of the detector and switches to an unregulated voltage supply whenever a fire is detected to supply the energizing current for audible and visual alarm indicators.

United States Patent 1 1 3,623,050

[72] Inventor AtsuhiroKojinu [56] v ReferencesCited Yokohama, Japan 11111151) STATES PATENTS P 776,985 2,769,121 10/1956 Rogoff 317/132 [221 FM 331: 3,258,758 6/1966 Byrd 340/228 [451 1 3,396,386 8/1968 Garfunkeletal. 340/409 [731 Asslgn" 3,500,394 3/1970 Egesdal 340/409 524,374 8/1894 Bernhardt. 340/333 223 3,225,341 12/1965 Devine 340/333x .521,2 6 7 1970 b 340 409 3 7 Ra er Primary Examiner-John W. Caldwell Assislan! Examiner-William M. Wannisky [54] ELECTRIC SOURCE DEVICES FOR FIRE ALARM Attorney-Chittick, Pfund. Birch. Samuels & Gauthier SYSTEMS 1 Claim. 2 DrawlngFlgs. [5.)] U s 340,228 I ABSTRACT: A fire alarm system uses a detector operated O n f a regulated voltage supply maintains the sensitivi- 340/227340/256 340/2lO3l7/l32 307/86 ty of the detector and switches to an unregulated voltage 307/ 179/5 supply whenever a fire is detected to supply the energizing 22 539 current for audible and visual alarm indicators.

228.1, 227, 333, 409, 256, 210, 41 1; 317/132; 307/66, 86, H6, H7; 325/492; l79/2 A, 5

' PATENTEDHUV 23 lBYI 3,623 ,050

G FIG. 2

INVENTOR ATSUHIRO KOJIMA BY mawhfvw, KC-J ,M 1: Guam ATTORNEYS ELECTRIC SOURCE DEVICES FOR FIRE ALARM SYSTEMS This invention relates to improvements in electric source devices forfire alarm systems.

Electric sources for fire alarm systems wherein their fire sensing means utilize fire detecting elements which sense occurrence of fire hazards by the variation in voltage across the elements, for example an ionization chamber and the like, generally require a suitable voltage stabilizer to maintain the sensitivity of the fire detecting elements at a definite value, in order to provide constant supervision.

In a prior source for a fire alarm system of the type referred to above, as the source is also used to energize lamps for indicating the operation of the fire alarm system and/or to ener gize a receiver thereof, the stabilized source is required to have sufi 'rcient capacity to satisfactorily operate the fire alarm system when a fire occurs. For this reason the source for a fire alarm system is required not only to be stable but also to have a large capacity, thus increasing the cost thereof.

THe object of this invention is to decrease the capacity of i the source. According to this invention in a fire alarm system {comprising a fire sensing means including a fire responsive ,4 element which senses a fire hazard by varying the voltage thereacross and a fire indicating means, and a receiver including a stabilized source for supervision, means to receive a signal from said fire sensing means and a fire alarm means, there is provided an electric source device characterized in that upon occurrence of a fire hazard said signal receiving means operates to disconnect the stabilized source from the fire sensing means and to connect an independent source to the fire indicating means and to the fire alarm means.

This invention can be more fully understood from the following detailed description when taken in conjenction with the accompanying in which:

FIG. 1 shows a connection diagram of one example of an electric source device for a fire alarm system embodying this invention and F IG. 2 shows a modified embodiment of the electric source device for use in a receiver.

Referring now to the accompanying drawing, FIG. 1 shows a circuit diagram of a fire alarm system embodying this invention and comprising a fire sensing means A, a receiver B and supply lines l and F interconnecting them. Fire sensing means A comprises a fire responsive element T which may be an ionization chamber, for example, connected to supply lines I and F at its terminals 1 and 2, respectively, a controlled rectifier S with one terminal connected to line I', and a parallel combination of a lamp L1 and a protective resistor R1 connected between the other terminal of the controlled rectifier and line F. Receiver B comprises a stabilized source E3 adapted to normally supply a stabilized voltage for supervision across lines I and F via a relay contact b2 and a relay G which receives a signal from the fire alarm system in a manner to be described later, and a series circuit connected across lines I and F and including a normally opened relay contact k3, a resistor R2, a push button P1 and a source E2 for said pilot lamp L1. The receiver also includes a source El for energizing relay circuits and an alarm device. A series circuit including an alarm buzzer b and a normally opened contact h5 and series circuit including an alarm lamp L2 and a normally opened contact H4 are respectively connected across source El. An

alarming relay H is provided with its one end connected to the negative terminal of source El and the other end to parallel connected normally opened contacts hl and g. A push button P2 interlocked with said push button Pl is included as shown. it is to be understood that contacts hl through I are operated by the alarming relay H while contact g is operated said receiver relay G.

The fire alarm system operates as follows:

When fire responsive element T detects the occurrence of a fire, it will supply a signal to the gate electrode of the controlled rectifier S from its output terminal 3. Thus the controlled rectifier S becomes conductive to light pilot lamp Ll through a circuit from stabilized source E3'via receiver relay 0, contact h2, line 1', controlled rectifier S, lamp L1 and protective resistor R1, and line I whereby to indicate the position in which the fire took place. Concurrently therewith the receiver relay 0 in the receiver B is energized to close its contact g, thus energizing alarming relay H from source El. As a result its contact k2 is opened whereas contacts I11, I13, I14 and k5 are closed and the alarm relay H is self-hold by contact hl. Opening of contact b2 and closure of contact 123 transfers the source for pilot lamp L] of the fire detecting means A from source E3 to source E2 thus continuing the lighting of the pilot lamp Ll. Contact '12 and k3 are designed to operate such that contact k3 is closed before opening contact h2, thus assuring continuous energization of the fire detecting means A. Closure of contacts I14 and its results in the energization of buzzer b and alarm lamp L2 from source El. Thus, it will be seen that source E2 is required to have a capacity only sufficient to maintain the controlled rectifier S in the fire detecting means A in the conductive state and to light pilot lamp Ll.'ln addition, the source E2 should have a sufficiently flat voltage. On the other hand, source El may be a direct current source which may fluctuate to some extent so long as it can continuously operate alarm relay H.

FIG. 2 illustrates a modified construction of the receiver which is identical to that shown in FIG. 1 except that a single source E2 is utilized for energizing both pilot lamp L1 and the alarm device in the receiver. However, since the modification shown in FIG. 2 operates in the same manner as that shown in FIG. 1, it is believed unnecessary to describe it again.

While in the above described embodiments only one fire detecting means A is connected to one circuit comprised by lines I' and F, it will be clear that any desired number of fire detecting means may be connected to one line. Similarly, the stabilized source E3 may be used commonly for a plurality of circuits.

Thus, according to this invention, the stabilized source is used only to sense the occurrence of the fire hazard and this source is automatically switched to other source for providing indication and alarm of the fire so that the stabilized source is required to have a small capacity only sufficient to supply a small current during normal supervision. in addition, as the current required for normal supervision is small a plurality of fire alarm systems can be connected to a single stabilized source. Thus, this invention makes it possible to greatly reduce the capacity of the stabilized source which is required to operate a sensitive fire detecting element in the fire alarm system.

What is claimed is:

l. A supervisory fire alarm system comprising:

a fire sensing station having a pair of line terminals normally substantially open circuited and across which are connected an ionization chamber and a signal controlled rectifier responsive to detection current flow in said ionization chamber to conduct current between said line terminals; a receiving station connected to said line terminals of said fire sensing station and including a stabilized voltage source, current responsive means, and a circuit connecting said source through said current responsive means to said line terminals to supply stabilized operating voltage from said source to said ionization chamber and said controlled rectifier;

an electric power source,

alarm means,

an alarm relay with latching contacts connected to said power source, and

a circuit connecting said power source to energize said alarm means when said alarm relay is energized;

switch means operated by current flow from said stabilized voltage source through said current responsive means to said controlled rectifier for energizing said alarm relay; and

switch contacts operated upon energizing said alarm relay to supply current to said line terminals from said power source and to disconnect said stabilized voltage source from said line terminals.

k i I I I 5 

1. A supervisory fire alarm system comprising: a fire sensing station having a pair of line terminals normally substantially open circuited and across which are connected an ionization chamber and a signal controlled rectifier responsive to detection current flow in said ionization chamber to conduct current between said line terminals; a receiving station connected to said line terminals of said fire sensing station and including a stabilized voltage source, current responsive means, and a circuit connecting said source through said current responsive means to said line terminals to supply stabilized operating voltage from said source to said ionization chamber and said controlled rectifier; an electric power source, alarm means, an alarm relay with latching contacts connected to said power source, and a circuit connecting said power source to energize said alarm means when said alarm relay is energized; switch means operated by current flow from said stabilized voltage source through said current responsive means to said controlled rectifier for energizing said alarm relay; and switch contacts operated upon energizing said alarm relay to supply current to said line terminals from said power source and to disconnect said stabilized voltage source from said line terminals. 